Conditioning the air within an enclosure has been accomplished by self-contained unit employing a refrigeration heat pump with the unit generally located within an opening in the enclosure. In order to both heat and cool the air within the enclosure, the reversible type refrigeration apparatus has been used including two heat exchangers, one located so as to allow recirculation of the enclosure air therethrough and the other located so as to allow the recirculation of outdoor air therethrough. The heat exchangers operate interchangeably as condensers and evaporators to both heat and cool the enclosure. Control means are provided by which reversal of the refrigeration cycle can be obtained.
The units are usually provided with sump areas located in the outdoor section of the unit at a level below the heat exchangers. Conduit means are provided for directing condensate collected by the indoor heat exchanger when it functions as an evaporator to the sump area, while condensate collected from the outdoor coil when it functions as the evaporator is also directed into the sump area. Condensate removal means operable in the cooling cycle directs the condensate from the sump into the outdoor coil functioning as the condenser to cool it and dispose of the condensate by evaporation. The condensate collected in the sump during the heating cycle when the outdoor heat exchanger functions as the evaporator cannot be disposed of in this manner and may, in fact, freeze since the unit may at times operate at below freezing temperatures. Water frozen in the sump area may in some instances result in locked fans which can result in blown fuses, burned out motor and other damages.
Some prior art attempts have provided drains in the sump area, such as disclosed in U.S. Pat. No. 2,777,303-Slattery, assigned to the General Electric Company, the assignee of the present invention. The patent teaches the use of a thermally responsive element that cooperatively opens the drain when the outside temperature falls below a predetermined temperature to drain the sum of any condensate that may have collected.
U.S. Pat. No. 2,982,110-Kramer appears to disclose an apparatus that selectively conducts condensate formed at the outdoor heat exchanger to the vicinity of the indoor heat exchanger during the heating cycle in accordance with predetermined humidity conditions in the vicinity of the latter heat exchanger, and treats the circulating air being heated by entraining the condensate therein. U.S. Pat. No. 4,136,529-McCarty, assigned to the General Electric Company, the assignee of the present invention, discloses an apparatus wherein the condensate collected in the outdoor sump in the heating cycle is disposed of by directing it to the indoor section where it is entrapped in the recirculating enclosure air and passed through the relatively warm indoor heat exchanger to humidify the air.